In the paper by G. Kobal and K. H. Plattig in the journal "Zeitschrift fur Elektro-Encephalograhie, Elektromyographie und verwandte Gebiete" (Journal of electro-encephalography, electro-myography and related fields), 9 (1978) pages 135 to 145, investigations are described in which the sensory quality. of smell can be checked by causing a test substance introduced nasally via a nasal probe to trigger a stimulus, which can be revealed in the electro-encephalogram (EEG).
In tests of this kind it is important to introduce the test substance, which is conveyed into the nose in gas or vapor form, in such a way that the expected stimulus depends only on the test substance and not on other changes, for example on changes in the flow rates or temperature values of the introduced gas or vapor. Because of the sensitivity of the encephalographic response to such stimuli, reliable measurement is possible only when one has succeeded in applying specific stimuli and excluding unwanted stimulating influences. The encephalogram can generally be assessed with the help of a computer.